Why do you need to keep pedalling at 70km/h (which is about 120rpm at 52/11) on every ride? You’re probably faster just tucking in anyway. Or are these very shallow downhills and you are trying to bomb it? But then spinning out at that gear at shallow gradient means you are pushing a lot of watts, every ride.
Don’t misunderstand, you do what you want to do, just that it’s bizarre to me.
It’s the only way I can do long intervals. Otherwise I get big time gaps in my work intervals. I also just like to keep pressure on the pedals. I aim for >90% pedaling, that is, less than 10% of my ride time coasting. I’m also a sprinter with a decent kick. 50t definitely wasn’t cutting it there.
But also, like @Neuromancer said, it’s more efficient to be in the middle if the cog. Smaller chainrings mean I’m on the edge (smaller cogs) more frequently.